Thread tensioning means for sewing machine bobbin case



y 1 w. A. AYRES 2,836,136

THREAD TENSIONING MEANS FOR SEWING MACHINE BOBBIN CASE Original FiledSept. 13, 1951 ZNVENTOR. MQwQwA/P 44 255 I rQTTOQ/MEYS United StateshatentO THREAD TENSIONING NIEANS FOR SEWING MACHINE BGBBIN CASE WaldemarA. Ayres, Lakewood, ()hio, assignor to White Sewing Machine Corporation,Lakewood, Ohio, a corporation of Delaware Original application September13, 1951, Serial No. 246,437, now Patent No. 2,728,315, dated December27, 1955. Divided and this appiication October 28, 1955, Serial No.543,539

8 Claims. (Cl. 112-229) This invention relates to a thread tensioningmeans for sewing machine bobbin cases.

This application is a division of my copending application Serial No.246,437, filed September 13, 1951 for Sewing Machine now Patent No.2,728,315, issued December 27, 1955.

Modern sewing machines of the lock stitch type conventionally employ arotary shuttle or book disposed beneath the bed of the machine forcooperation with the needle when the latter penetrates the material andpasses through the needle opening in the bed. In such machines therotary shuttle carries a thread bobbin which supplies the thread forinterengagement with the thread carried by the needle, which bobbin isenclosed in a bobbin case removably supported upon the center pin orstud of the shuttle and retained in place by a latching means.

Bobbin cases of the type mentioned above also conventionally employ athread tensioning means for applying a frictional force or tension uponthe thread coming from the bobbin. Where a latching means, as mentionedabove, is utilized upon the bobbin case, the tensioning means ordinarilyis provided upon the side Wall of the case. This has resulted innumerous difiiculties with respect to providing adequate adjustabilityof the tension, the conventional means being the use of a screw threadedinto the side wall of the case for effecting such adjustment. Since theside wall of the case is, however, relatively thin, very littleadjustment is provided and the threads of the screw are quite delicateand hence are easily stripped. Moreover, the adjustment of such atension means requires the use of a screwdriver or similar tool' and thedegree of tension is not readily determinable except by trial and error.

An. object of the invention is the provision of an improved threadtensioning means for a bobbin case which improved thread tensioningmeans as defined above and which includes means for readily indicatingthe frictional force or tension upon the thread for any adjustedposition of the tensioning means.

Further and additional objects and advantages inherent herein but notspecified will become apparent during the detailed description of anembodiment of the invention which is to follow and which embodiment isillustrated in the accompanying drawing forming a part of thisspecification and wherein,

Fig. 1 is a view, principally in side elevation, but with certain partsbroken away and others shown in section, illustrating the presentlypreferred embodiment of the improved bobbin case provided with a threadbobbin and latched in place upon a rotary shuttle, only a portion of thelatter being. shown;

Fig. 2 is a front elevational view of the bobbin case shownin Fig. l;

Fig. 3 is a view taken substantially on the line 3-3 of Fig. 1 withcertain parts removed and other shown in section and with the latchingmeans illustrated in the position in which the case is unlatched fromthe shuttle; and

Fig. 4 is a view, partially in side elevation and partially in section,the view being taken substantially onthe line 44 of Fig. 3 and showingthe case detached from the shuttle and the manner in which the bobbin isretained in the case when the latching means is moved to thus detach thecase.

In Fig. 1 of the drawings, 10 designates a conventional rotary shuttlefor a sewing machine which is constructed in a well known manner andconnected for rotation by the mechanism of the machine. Since thisconstruction is well known in the art, the details thereof are not hereillustrated or described. For the present purpose it is sufiicient tonote that the shuttle 10 has a forwardly extending center pin or stem11, integral with or rigidly connected to the shuttle, the former beinghere illustrated. This pin or stem 11 provides the support for a bobbincase 12 and for a thread bobbin 13 which is enclosed within the case. Ashere illustrated, the bobbin case 12 is formed of metal and is generallycup shaped with a substantially planar face 14, which is raised slightlyadjacent,

the periphery and is united with a substantially cylindrical side wall15. A portion of the side wall 15 is struck up therefrom in the form ofan integral finger 16 which is adapted to engage a stationary part ofthe machine and thereby retain the bobbin case stationary duringoperation of the machine as is well known in the art.

The planar face 14 of the bobbin case has a central opening in which atubular member or sleeve 17 is positioned. This member has an integralshoulder 18 thereon engaged with and secured to the inner surface of thebobbin face by brazing, welding or the like. The tubular or hollowmember 17 extends axially in both directions, from the shoulder 18, theportion extending to the left, as seen in Fig. I. being adapted to fitwithin the central opening of the thread bobbin 13 and provide a journalherefor, the inner end of this portion of the sleeve or member 17 beingreceived in an annular recess in the shuttle 19 about the center pin orstem-11. The clearance between the pin or stem 11 andthetubular member17 is greatly exaggerated in the drawings to facilitate identificationof the parts and because the scale of the drawing is several times thatof the actual mechanism.

The portion of the hollow sleeve or member 17 extending forwardly, or tothe right of the shoulder 18 as viewed in Fig. 1, projects beyond theouter surface of the face 14 of the bobbin case and is threaded for apurpose hereinatter described.

T he face 14 of the bobbin case is provided with a latch member,generally designated 19, which is here shown as a three armed leverpivotally supported on the outer surface of the face 14 by a shoulderedrivet or stud 2G. One'arm'21 of this lever 19 provides a latch portionwhich is adapted to pass through a slot or opening 22 in the tubularmember 17 and engage in an annular groove 23 of the pin or stem 11 asshown in Figs. 1 and 2. The latch member or lever 19 isnormally urged tothis position by a spring means 24 which is here shown as formed fromspring wire with one end engaged under an integral projection 25 of thelatch portion 21 and with the other end restingagainst the inner surfaceof the side wall 26 of a cover member 27, see Figs. 2 and 3. Theintermediate portion of the spring 24 is coiled or looped about the stud20.

A second arm 28 of the latching member or lever extends over the face 14of the bobbin case and has angularly' extendingportion 29 directedrearwardly i piece of metal.

ibility in the, arm 28 is to insure positive release of the the caseadjacent the integral finger 16 and in a region ,where a portion of theside wall 15 hasbeen removed so that this projection or portion 29normally extends adjacent a flange 30 of the thread bobbin butheldspaced 5 therefrom due to the biasing action of the spring means 24.However, when the latchsmember or lever 19-is rocked against the biasingaction of the spring means .24,

that is, counterclockwise as viewed in Figs. 2 and 3, the

[portion 29 of the arm 28 moves into engagement with J the flange 30 ofthe bobbin 13 whilethe'arm 21 of th e lever 19 is moved-from engagementwith respect to the groove 23 of the pin 11. Consequently, the bobbincase 12 is unlatched from engagement with the shuttle and i the bobbin13 is held within the case so that the bobbin 'does not fall from thecase while the latter is being withdrawn from or placed uponthe'pin'll'of the shuttle, To facilitate this movement of the lever 19,it is provided with a third arm 31 intermediate the arms '21 and 28and'having an integral outwardly extending portion 32 for convenientengagement by a' finger or thumb of a the operator, it'being evidentthat the operator has 'only to press upon the projection 32in acounterclockwise direction, as viewed in .Figs. 2 and 3, to achieve theaforementioned unlatching of the bobbin case and simultaneous engagementof thearm 28 with the bobbin. 7

An important feature resides in the provision of construction'isefiected by forming this arm of lesser .cross section than that of theother arms of the lever 19,

the entire lever being preferably stamped from a single This provisionof resilience or flexbobbin case from the shuttle pin 11 even though thebobbin 13s.v be oversize or some other cause results in the projectingportion 29 of arm 28 engaging the flange 36 before the latch portion 21has moved entirely out of the groove 23. In'theevent of such acontingency, the arm 28 simply yields relative to the remainder of thelever 19 so that the portion 21' can still be moved to a posi 7 tion inwhich it is completely out of the groove 23. The proportions of theparts and the dimensions of the lever are such that this relativemovement between the arms does not exceed the elastic limit of the leverso that even repeated flexing of the arm 28' does not result in damagethereto. Moreover, the force'required to efiect such relative movement'between the arms is not such as to require the use of to'ols'. a

The aforementioned cover member 27, providing .an abutment for the freeend of spring 24, is'secured to the face 14 of the. shuttle case by acover retaining cap '33 which is internally threaded for cooperationwith the threads on the outer endof the tubular memberl'l, see Fig. -l,the cap 33 being provided with spaced apertures '34 or, othersuitablemeans for engagement by a tool for manipulating the cap.; The portion ofthe cover mern-s I ber 27 opposite arm 31 of'the lever 19 ispreferablyprotively thin metal and has a radius of curvature slightlyless than that of the side wall 15 so that when placed thcreabout thetensioning member '39 has a portion spaced from the surface of the sidewall. This tensioning member extends about a portion only of theperiphery-of the side wall and has one end secured thereto with theother end substantially free so as to allow passage from therebeneath ofthe thread from the bobbin and to exert a frictional force or tension onthe thread.

5 In the present construction, the tensioning member 39 has an integrallug or tonguefll) adjacent one end which is received in asuitable slotin the side wall of V the bobbin case thus preventing circumferentialshifting flexibility or resilience of the arm 28, which in the presentvided with :an integral.v outwardly extending portion for engagementby afinger or thumb of the operator when the latch member is being utilized;it being evident that the operator will place a thumbonfeither theportion32 or 35 and a finger on the other of these portions to cited theaforementioned rocking of the lever. Suitable means, such as an integraltongue'36 fitting in an openings37 of the face'14 is provided to preventary cuate displacement of the cover member 27.

The sewing thread, notzshown, carried by the bobbin 13 is brought fromthe interior of the bobbin case to the V exterior thereof through anopening 38 in the side wallof the case,- which opening 'cornprisesadiagonal slot endmg ina circular hole intermediate the sides of thesidewall, see Fig. l. A tensioning'means for the thread thus broughtexteriorly of the case is provided by a re s silient'tensioning member39 which is arcuate with a radius of curvature difierent from that ofthe side wall 15.

l The'tensioning member 39 preferably isiformed of rein peripheralextent of the lug 42. cannot accidentally become disengaged, it' beingimpos- 1 sible forthe member 44 to drop out of manages 'due' ofthetensioning member. The other end of the tensioning member has arelatively broad lip portion 41 extending beyond the opening 38 for thethread so that the latter may pass from beneath the lip to its point ofV utilization. Adjacent the lip 41 and at one side thereof,

the tensioning member 39 has a second integral lug or.

by means of a sliding means or member 44 which passes throughaligned'elongated slots 45 in the tensioning mern ber 39 and thesidewall 15. This sliding means is here shown as a double headed stud,the inner head of which is of smaller diameterthan the outer and isdisposed in a milled groove 46 on the inner surface of the side wall 15,adjacent the slot 45. The outer head of the member 44 bears against theouter surface of the tensioning member 39 and the distance between theheads of the members 44, is suchthat'as the latter is slid through thealigned slots 45, upwardly as shown inthe'drawings, the curvature of themember. 39 'is altered so that the lip portion 41 exerts increasedfrictionalforce upon the thread, thus increasing the tension thereon, Inorder that the amount of frictional force or tension thus applied to thethread may be readily determined, suitable calibrations and/or indicia47 aresprovided adjacent the slots 45 for co- 7 operationwith the member44 and the latter may be provided with an indicium such calibrations.

As will be seen fromFig. 4; the slot in the side wall 15 terminates atits lower end in an enlarged opening 48.

A similar opening is provided at the end of the slot in the tensioningmember 39. ,These openings are slightly larger than the diameter of theinner head of the member 44 and are out of alignment when the lug ortongue is received in the cooperating slot so that'the sliding member 44and the tensioning member 39 cannot he accidentally disengaged from eachother or from the side wall 15;

In attaching the tensioning member39 to the side wall;

15, the lug or tongue. 42 is inserted in the slot 43. Then,

while the enlarged opening. at the end of the slot in the V tensioningmember is aligned withitheenlarged opening 48 in the side wall 1.5, themember 44"isfinserted therein;

At this time the lug 40 will berestin'g upon a portion or the side wall15 spaced from the cooperating slotin a counterclockwise direction, asviewed in the' drawings, a slight pressure beingexerted upon' thetensioning member' so that the inner head .of the member can be.

disposed inwardly of the inner surface of side wall'15. The tensioningmember 39 and sliding member 44 are ment, this mov me'n er thetensioning member being permitted by virtucof the slot 43, being longerthan the or markfor cooperation with I The parts thus assembled a es, 1as:

to. the fact: that the enlarged heads thereon cannot pass therethroughand the enlarged openings such as 48- are prevented from slipping intoalignment by the lug 40. The tension exerted by the member 39, however,is readily adjusted by sliding movement of the member 44 upwardly in thenarrow portions of the slots 45 which is etlected without the need ofany tools.

It is believed that the operation of the device will now be readilyapparent from the detailed description of the construction thereof. Theuse of the device, however, may be briefly summarized as follows:

Let it be assumed that the bobbin case 22 has the latch and tensioningmeans assembled thereon as shown in Fig. 2 and which is the form inwhich it would be supplied to the user. A bobbin 13 having sewing threadof the proper size and color thereon is then placed upon the tubularmember 17 as. shown in Fig. 4 and the end of the thread is broughtthrough the opening 38 and led therefrom and from beneath the lip' 41intermediate the upper end of the latter and the lug 42. The tension tobe exerted upon the thread is then adjusted to a predetermined value bymoving the slidable means or member 4-; to a position adjacent thatindicium or calibration 47 indicative of the desired tension thusdeflecting or altering the curvature of the member 39 so that the lipportion bears with a predetermined force upon the thread thereoeneath,the outer end of the lip 41 being reverse curved slightl see Figs. 2 and3, to facilitate proper engagement of the inner surface of the lip withthe thread. This operation of tension adjustment is simply effected bythe operators thumb engaging the member 44 and sliding the latter to theproper position.

ft l" led from beneath the lip- 41, and with the tensionv on the threadadjusted, the case is then ready to be placed in cooperation with theshuttle. Since the shuttle is normally disposed. at a location whichrequires turning of. the case to either a horizontal or verticalposition, and which might result in the bobbin falling from the case,the operator will now engage the projections 32 and 35, moving theformer towards the. latter so that the arm 2% is moved to brim theprojection 2? into engagement with. flange 3d and. move the latchportion 23 to a position which it may be passed over the end of the pin33 to the shuttle. With the latching means held in this position, thebobbin case may be inverted or otherwise turned without fear of thebobbin falling therefrom, thus facilitating positioning of the bobbincase with the, tubular member sleeved upon the pin 11. as shown in Fig;l. The latch means 19' may then be released so that the spring 2 5 movesthe portion 21 into the groove 23 and the arm 23 to free the projection29 thereon from the flange 3% or" the bobbin. The case is then latchedto the shuttle and is ready for use in sewing operations. In the eventthe operator has released the latching member 19 before the portion 21has cleared the end of pin 11, the bobbin case may nevertheless bereadily properly positioned without again operating the lever 19 bysimply exerting axial thrust upon the case in a direction toward theshuttle it When this is done the outer end of the pin 11 engages thelatch portion 21 of the lever 59 and cams the latter outwardly againstthe force of the spring 24, as the bobbin case is moved to the left, asviewed in Fig. l, the latch portion 21 thereafter snapping home in thegroove 23 under the force of the spring 2 when the parts have reachedthe positions e32 reverse operations. That is to say, g the portion 32of the lever 19 toward the cover, the latch portion 21 is moved o in thegroove 23 so that the bobbin case may be moved axially from the pin 11.in the event the bobbin i3 is oversize, or for any other reason theprojection 29 engages the flange 30 of the bobbin before the bobbin inplace in the case and the thread;

die portion 21 of the lever is freed from the groove 23,.

the bobbin case may nevertheless be unlatched by continued pressure onthe portion 32. This causes the arm 28 and/or the projection 29 to yieldor flex relative to the portion 21 so that the latter may be moved tothe necessary extent to effect unlatching even though further rocking.of the arm 2 is prevented.

Although the tensioning means has been shown as having. integral tongueor lugs cooperating with slots in the side wall of the bobbin case toprevent improper movements of the tensioning member, a similar resultcould be achieved by riveting or otherwise securing the lower end of thetensioning means to the side wall of the bobbin case. Furthermore, whilethe slide member or means 44 is shown as having round heads, the headsand has a substantially cylindrical. side wall provided:

with an opening therethrough for passage of thread from the bobbinexteriorly of the case, an arcuate resilient thread tension memberhaving a radius of curvature different from that of the said side walland extending about a portion of the external periphery of the latterand directly connected thereto, means on said tension member adapted toengage the thread from the bobbinexternally of said side wall andcooperate with the latter to exert therewith a direct frictionaltensioning force on, the thread, the said tension member and theadjacent portion of the side wall of the bobbin case having alignedlongitudinal slots therethrough in a location where the tension memberis spaced from the side wall, and means.

slidably positioned in said slots and engaging the inner surface of the.said side wall and the outer surface of the tension member to alter theradiusof curvature of said tension member and thereby vary thefrictional force on said thread.

2. In combination with a bobbin case for av sewing machine, which caseis adapted to receive a thread bobbin and has a substantiallycylindrical. sidewall provided:

with an opening therethrough for passage of thread from the bobbinexteriorly of the case, an arcuate resilient thread tension memberhaving a radius of curvature different from that of the said side walland extending about a portion of the external periphery of the latterand directly connected thereto, means on said tension member adapted toengage the thread from the bobbin externally of said side wall andcooperate with the latter to exert therewith a direct frictionaltensioning force on the thread, the said tension member and the adjacentportion of the side wall of the bobbin case having aligned longitudinalslots therethrough in a location where the tension member is spaced fromthe side wall, means slidably positioned in said slots and engaging theinner surface of said side wall and the outer surface of the tensionmember to alter the radius of curvature of said tension member andthereby vary the frictional force on said thread, and means adjacentsaid slidable means and cooperating with the latter for indicating theamount of frictional force applied to the thread for any given positionof the slidable means along said slots.

3. In combination with a bobbin case for a sewing machine, which case isadapted to receive a thread bobbin and has a substantially cylindricalside wall provided with an opening therethrough for passage of threadfrom the bobbin exteriorly of the case, an arcuate resilient threadtension member having a radius of curvature different from that of thesaid side wall and extending about a portion of the external peripheryof the latter and having portions directly engaging said side Wall, co-

: operating means on said tension member and side wall preventingdisplacement of the former circumferentially of the latter, means onsaid tension member adapted to engage the thread from the bobbinexternally of said side wall and cooperate with the latter to exerttherewith a direct frictional tensioning force on the thread, the saidtension member and the adjacent portion of the side wall of the bobbincase having aligned longitudinal slots therethrough in a location .wherethe tension member is spaced from the side wall, and means slidablypositioned in said slots and engaging the inner surface of said sidewall and the outer surface of the tension mem ber to alter the radius ofcurvature of said tension member and therebytvary the frictional forceon said thread.

4. The combination as defined in claim 3 wherein the I said longitudinalslots in the side wall and said tension member terminate at one end inenlarged openings of sufiicient size to permit passage therethrough ofsaid slidingmeans when the said openings are aligned, the said openingsbeing disposed out of alignment when the said tensioning member isoperatively assembled on said side wall with the said cooperating meansin engagement.

. 5. In combination with a bobbin case for a sewing machine, which caseis adapted to receive a thread bobbin and has a substantiallycylindrical side wall'providediwith an opening therethrough for passageof thread from'the bobbin exteriorly of the case, an arcuate resilientthread tension'member having a radius of curvature less than that of thesaid side wall and extending about a portion of the external peripheryof the latter, means adjacent one end of said tension member cooperatingwith'said side wall to prevent displacement of the formercircumferentially of the latter, an integral portion of said ten- 'sionmember at the other end thereof adapted to engage the thread from thebobbin externally of said side wall 7 and cooperate with the 'lattertoexert therewith a: direct frictional clamping forceon the thread, thesaid tension member and the adjacent portion of the side wall of thebobbin case having aligned longitudinal slots therethrough in a locationwhere the tension member isspaced from the side wall, and means slidablypositioned in said slots and engaging the inner surface ofsaid sidewall'and the outer surface of the tension member to alter the radius ofcurvature of said tension member and thereby vary the frictional forceon said thread.

' 6. In combination with a bobbin case for a sewing machine, which caseis adapted to receive a thread bobbin and has a substantiallycylindrical side wall provided with an opening therethrough forpassagejof thread from the 7 bobbin exteriorly of the case, an arcuateresilient thread tension member having a radius of curvature-less thanthat of the said side wall and extending about a portion of the externalperiphery of the latter, an integral tongue on said tension memberengaging in an opening of. said sidewall to prevent displacement of thetension member circumferentially of said sidewall, an integral portionadjacent an end of said tension member adapted to engage the thread fromthe'bobbin externally of said side wall and cooperate with the latter toexert therewith a direct frictional tensioning force on the thread, thesaid tension member and the adjacent portion of the side wall of thebobbin case having aligned longitudinal slots therethrough intermediatethe ends of said tension member in a location where the latter is spacedfrom the side wall, and means slidably positioned in said slots and'engaging the inner surface of said side wall and the outer surface ofthe tension member to alter the radius of curvature of said tensionmember and thereby vary the frictional force on said threadf 7. Thecombination as defined in claim 6 and further comprising calibrations onsaid tension member adjacent the longitudinal slot therein cooperating.with said slid able means to indicate the frictional force upon thethread for any position of said slidable means.

8. In combination with the bobbin case for a sewing machine, aresilientthread tension member having an elongated slot thereinterminated in an enlarged opening,

a corresponding slot and openingin said bobbin case, a member adapted toslide insaid slots and provided with.

spaced heads larger than the width of said) slots and with at least oneof theheads smaller than said openings so thatfthe said one head of saidheaded member'is insertable through said openings when they are aligned,

'and means preventing alignment of said openings after.

the said headed member has been slidably positioned in said slots,whereby'the tension of said tension member may be adjusted by sliding ofthe headed member in said slots and the headed member cannot heaccidentally displaced from the case.

' References Cited in the file of this patent UNITED STATES PATENTS2,034,506 Colegrove et a1. Mar. 17, i936 Robert Nov. 15, 19491 p

